The flume hdfs sink can be configured to roll based on size, # ofevents, or time.

hdfs.rollInterval30Number of seconds to wait before rolling currentfile (0 = never roll based on time interval)hdfs.rollSize1024File size to trigger roll, in bytes (0: never rollbased on file size)hdfs.rollCount10Number of events written to file before it rolled (0 =never roll based on number of events)